The present invention relates to a surface heating device to be used in a seat or the like.
A conventional surface heating device 21 commonly includes a heating element disposed on a supporter 28 as shown in FIG. 31. The heating element is one of the following:
(a) A heating element 22a, as shown in FIG. 29, having a plurality of conductors 25a coated with an insulating coating 26a; or
(b) A heating element 22b, as disclosed in Japanese Utility Model Laid-open Publication 60-80690, where a conductor 25b is wound spirally on a synthetic fabric core 27 and coated with an insulating coat 26b as shown in FIG. 20 for an improved strength against tension and bending.
FIG. 27 illustrates the surface heating device 21 installed in a seat 20 for a vehicle. Even if a heating element 22 has a diameter of 0.5 to 1 mm, the surface heating device 21 may make a driver or a passenger aware of an uncomfortable projection on a surface cover 23 when he/she is seated. It is hence desired to decrease a thickness or diameter of the heating element 22.
FIG. 28 is an enlarged cross sectional view of a region where the surface heating device 21 is installed in the seat 20 for a vehicle. In a conventional manner, a pad 24 provided under the surface cover 23 of the seat 20 needs to have a thickness of 20 to 30 mm for preventing the heating element 22 from making him/her aware of an uncomfortable projection on the surface cover 23. The surface heating device 21 is provided beneath the pad 24.
FIG. 32 is a cross sectional view of a region where the surface cover 23 of the seat 20 has a hanging section provided in the surface cover 23. The hanging section is usually provided at the surface cover 23. The hanging section at the surface cover 23 includes a hanging strip 30 joined to the surface cover 23 and the pad 24 at a sewing portion 33. A hook ring 32 links a fitting 29a joined to the hanging strip 30 and a fitting 29b embedded in a main pad 31.
If the surface heating device 21 is placed under the surface cover 23 of the seat 20 and directly stitched together with the hanging strip 30, the heating element 22 may be injured or cut by a stitching needle. For avoiding such a problem, the surface heating device 21 has an opening 33, as shown in FIG. 31, through which the hanging strip 30 extends, and the heating element is protected from being stitched with the strip 30.
As a result, the pad 24 inhibits the surface heating device 21 from being located directly under the surface cover 23 of the seat 20 and, as a heat insulator, prevents the surface cover 23 from being quickly heated. Therefore, heating quickly the surface cover 23 of the seat 20 requires a large power consumption by the surface heating device 21. However, a capacity of a battery in the vehicle limits heating speed.
The conventional heating element 22a, as shown in FIG. 29, has conductor 25a coated with insulating coat 26a for protecting the conductor from separating and for improving protection strength. Due to the insulating coat 26a, when the heating element 22 is connected to a power supply, the insulating coat 26a has to be removed at a jointed portion of the heating element 22.
The heating element 22 in the surface heating device 21 installed in the vehicle seat 20 requires a small thickness or diameter. Furthermore, the heating element 22 is repeatedly stressed by a weight during sitting of a person on the seat 20, and thus needs a counter measure against being injured and disconnected.
A surface heating device is provided which includes a heating element fabricated by braiding plural conductors, and a flexible supporter supporting the heating element thereon.
The heating element fabricated by braiding plural conductors has a small thickness or diameter, thus being inhibited from providing a passenger with an uncomfortable touch when he/she is seated and from projecting on a surface cover of a seat. Also, the surface heating device requires a pad having a reduced thickness and thus allows the surface cover of the seat to be heated up rapidly.
The heating element made from braided conductors is strong against being bent by a weight of a seated passenger because a stress exerted on the heating element is dispersed on the conductors. Furthermore, the conductors are protected from separating from each other, and therefore, no insulating coat is necessary.